Get one ECC control

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuinely non-obvious context beyond that: summaries are the project's own paraphrasing and the authoritative text lives at a linked page, which tells the agent how much to trust the returned wording.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, zero filler. The core action and returned fields are front-loaded, and the provenance caveat is placed at the end where it belongs.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, so the description carries the burden of return-value disclosure, and it lists the returned fields and their provenance. It does not mention behavior on an unknown/malformed ID, which is the one remaining gap for a deterministic lookup tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, setting a baseline of 3. The description earns above that by documenting that the id accepts multiple equivalent formats (dashed, dotted, or unpunctuated), which the schema's single "1-5-1" example does not convey; lang and response_format remain schema-driven.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb+resource ("Get a control by ID") plus an enumeration of exactly what comes back: summary, subdomain, domain, official page, and ISO 27001 / NIST CSF 2.0 mappings. The ID-format examples ("2-8-3", "2.8.3", "283") make it unmistakably a single-record lookup, distinguishable from ecc_search_controls.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the agent must infer that this is the tool for when it already has a control ID. No when-not guidance and no explicit routing to the search/crosswalk siblings is given, so the discriminating condition is left to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.